My 5 yr old was molested by her step-sis, CPS will not help. What can I do?

I have two daughters, ages 13 and 5. My fiance has a 13 year old daughter as well. I will call her S. My five year old I will refer to as J.

His daughter, S, was molested by her mother. He has full custody of this child.

Recently I have suspected that something might be going on with S doing inappropriate things to J.

My suspicions were confirmed when J tried to put something in my vagina. I am a grown woman, and I told her that was wildly inappropriate. J then whispered in my ear, "But I don't mind when S does it to me"

I dropped it at that moment. I called the police, the police questioned her, and she denied everything. They refuse to act unless my innocent 5 year old daughter admits to the police that J did something to her.

I'm destoryed by this, this is my 5 year old baby we're talking about. Is there literally anything else I can do??

~Devistated K

Edit: I forgot to add that I am in the United States, Florida specifically. Edit #2: CPS is involved, J is in counselling already, and S is starting it as soon as humanly possible.